For example, semiconductor manufacturing process includes a step of carrying-out thin disk-shaped semiconductor wafers in the horizontal direction from a hoop where the semiconductor wafers are stored and then conveying said semiconductor wafers to a treatment device for performing a predetermined treatment. A hand portion provided to a distal end portion of a robot arm is used for conveying the semiconductor wafer.
When carrying-out the semiconductor wafers from this hoop using the hand portion, there is a risk that the semiconductor wafers could fail to be carried-out. This results in an unsuccessful treatment of a predetermined number of semiconductor wafers. Accordingly, a configuration is presented where a sensor for detecting the presence of semiconductor wafers is provided to the hand portion so as to accurately carry-out the semiconductor wafers (refer to PTL 1).